Reversed cycle heating system



M y 1942. K. P. BRACE EI'AL e- 2 REVERSED CYCLE HEATING SYSTEM OriginalFiled April 2'7, 1955 2 Sheets-Sheet l INVENTORSZ ATTORNEYS.

May 26, 1942. p, BRACE ET AL Re. 22,100

REVERSED CYCLE HEATING SYSTEM Original Filed April 27, 1935 2Sheets-Sheet 2 INVENTORS.

ATTORN EYS.

Reissued May 26, 1942 mzvuassncrcm HEATING SYSTEM Kcmper P. Brace, SouthBend, Ind., and Robert B. P. Crawford, Athens, Ga.

Original No. 2,135,742, dated Serial No. 18,685, April 2'1,

November 8, 1938, 1935. Application for reissue October 17, 1939, SerialNo. 299,910

7 Claims.

This invention relates to air conditioning -systems and moreparticularly to systems for heating and cooling a building by what isknown as the reversed refrigerating cycle, and one of its objects is toreduce the cost of heating by such systems.

A further more specific object is to provide controlling mechanism forheating systems which will limit operation of the system at capacityload only to certain hours of the day.

Further-objects and advantages will become apparent from the descriptionwhich follows.

Referring to the accompanying drawings which are made a part hereof andon which similar reference characters denote the same parts thruout,Figure 1 is a perspective view of the system,

and

Figure 2 is a view of some of the details showing a single operatingmechanlsm for changing from a heating to a cooling system.

. In carrying out the objects of the invention, use is made of themechanical heat pump known as the reversed refrigerating cyc1e.-Refrigeration is an exchange of heat from one medium to another,resulting in the cooling of one and the heating of the other. Therefrigerating cycle is essentially a heat pumping cycle which is usedfor removing heat from one body or medium at one temperature anddischarging it into another body. or medium at a higher temperature. As

would be expected from the fundamental law oi .thermodynamics, thegreater the temperature difference between the cold body or medium fromwhich heat is removed and the body into which it is delivered, thegreater is the amount of energy required to pump a unit quantity of heatfrom the.cold body to the warmer body or medium. I r

The use of the refrigerating cycle for cooling a building is relativelysimple. The heat of the room is taken up by some suitable medium as citywater, well water, air or water from a cooling tower or spray pond.Heating a building by the refrigerating cycle, however, presents somedifiiculties. In the first place,.under normal conditions, the heatingload or heat pumping duty is higher during the heating season than isthe corresponding cooling load during the cooling season. In otherwords,it requires considerable more energy to heat a building when heatis required than it does to cool the building when cooling is required.In the second place, while a medium into which heat may be conveyedduring the cooling season is always available, a suitable medium fromwhich heat may be obtained for heating a building is not alwaysavailable.

'Our system provides means for making available a medium from which heatmay be obtained at very low cost. We propose to make use of the heat inartesian or underground well water for supplying heat necessary forheating a building by the refrigerating cycle. This medium is idealbecause it is inexpensive, plentiful, easy to handie and because inpractically all localities which require winter heat its temperature isconstant thruout the .year, at values ranging from 48 to 65 degrees F.Due to the high temperature of artesian well water, the temperaturegradient against which the refrigerating cycle must pump heat is low,hence the overall efficiency of the system is high. We propose to usethe artesian water mentioned above not only as a source of heat for therefrigerating cyclebut also as-a means for reducing the total heatload-required for heating the building. We dothis by using the wellwater to warm the incoming air supplied to the building. By raising thetemperature of coldair to within a few degrees of the temperature of thewater, the additional heat necessary to raise the air to the desiredtemperature is considerably reduced. In heating a building, obviously,it is necessary to supply only suflicient heat to take care of heatlosses. These heat losses are due to two principal causes.- First, bytransmission of heat by conduction thru the walls of the building,- theglass,

etc.. With well constructed building this loss.

may represent fifty per cent of the losses. The other loss is due to theinfiltration of air'thru the cracks in doors, windows and other places.The amount of this infiltration depends upon the type of construction ofthe building, the amount of the building exposed'to the wind, thevelocity of the wind, etc. The maximum innltration'under worstconditions'amounts to from one half to one and one half air changes perhour. In order to' maintain the room or building at the desiredtemperature this air must be heated at this rate,

It has been found that infiltration can be prevented to a large degreeby supplying enough outside air to the building thru the ventilatingsystem to create an internal air pressure equal to the external windpressure on the windward side of the building. In general the amount oiair necessary to be supplied to a building to prevent infiltration isequal to the amount which would enter by infiltration if no outside airwere supplied, that is, from one half to one and one half air changesper hour.

If this entering air can be heated at little or no cost, considerableeconomy will be effected. As stated we propose to beat this air byartesian well water. This can be done because in most climates-where theoutside temperature may go as low as zero degree, the

temperature of the available artesian water may be as high as 65 degreesF. With this water at this temperature it is posisble to heat theincoming air at least to 55 degrees F. Aswill be apparent this takescare of a large part of the heat loadfor the building.

We propose to reduce the cost of operation of the system by reducing theoperation of the system at certain times in the day during which periodsthe greatest demands are made upon the power system. This enables us tooperate at less cost for power.

Wherever electricity is being used in large quantities-the rate ofcharge for current is usually based on two things, namely, the energycharge based upon the actual amount of current used, and the demandcharge based upon the maximum rate at which the current is used at agiven instant. Usually this demand charge is figured as so much perkilowatt of maximum demand which occurs on the power company's peakperiod. If the current consumption can be arranged so that little or noenergy is consumed between hours limiting the companys peak period, thedemand charge canbe greatly reduced,

In the District of Columbia, for example, the demand charge for currentconsumed between the hours of 4:30 and 8:30 p. m. is $2.00 per month perkilowatt of maximum demand, whereas the demand charge for currentconsumed at other times of the day is only $1.00 per month per kilowattof maximum demand. Therefore, it would be advantageous to arrange thesystem so that not more than one-half of the normal current consumptionshould be used between the hours of 4:30 and 8:30 p. m. in the Districtof Columbia. This invention provides means for automatically reducingthe consumption of current during certain periods of the day, whichperiods may represent the'peak demands made upon the power system.

In the drawings niuneral i indicates a room to be heated or cooledhaving ducts II and I2 thru which air is supplied to and drawn fromtheroom by fan M which is operated by motor l5. Fresh air from the outsideof the building is supplied thru duct l3. The fresh air and the returnedair are mixed in the conditioning chamber I6 and discharged into theroom.

At II is shown a refrigerant compressor which is operated by a motor 60.Numerals l8 and I9 indicate inlet and discharge passages to and from thecompressor. Refrigerating fluid to and from the compressor passes thruvalve 20, the position of which valve determines whether the gas fromthe compressor passes thru line 2| or '22. When operating as a heatingsystem, the valve will be in the position shown in Figure 2, in whichcase the passage 23 of the valve will connect discharge line !9 withpipe 2| and the passage 24 will connect suction pipe IS with pipe 22.Positioned in the conditioning chamber I6 is a heat exchange unit 25consisting of a coil 26 thru which hot gas'from the compressor passes.The cool air passing thru chamber lfi passes over the coils 2B andcondenses the gas therein, the heat of condensation being taken up bythe air. .Liquid refrigerant is returned thru pipe 29, valve 21, pipe 30and expansion valve 28 to the evaporator 3|. The expanded refrigerant iswarmed in the shell 3| by water passing thru pipes 33, 34 and coil 32.The direction of flow of water thru the coil and pipes 33 and 34 isdetermined by the position of the f From the evap- .water is circulatedby a pump 4| and pipes 42 and 43, the pump drawing water from anartesian well.

The position of the valve 36 will determine the direction of flow thruthe element 3|. When the system is operating as a heating system the,valve will be in the position shown in Figure 1. The

4 element 3| then operates as an evaporator and it is necessary to warmthe gas before it passes to the compressor. :When operating as a coolingsystem the element 3| will operate as a condenser. When the valve 36 isin the position shown in Fig-- ure 1, the pump will draw water from theartesian well and circulate it thru the heater 40, pipe 43, passage 38in four way valve 35, pipe 33, coil 32, pipe 34, valve passage 31 andpipe to waste. The pump 4| must deliver a sufiicient volume of water towarm the air in duct i3 and in coil 32 without reducing the temperatureof the water to the freezing point.

The pump 4| is operated by current supplied thru lines 48 and 43 whichare connected to lead in lines 4-1 and 46. A thermostatically.controlledswitch 50 opens circuit thru lines 48 and 49 when the temperature of theincoming air is above the temperature of the well water.

and compressor Circuit to the motor for operating the pump 4| iscontrolled bya relay switch 5| which switch is controlled by currentsupplied thru lines 52 and 53, from the time clock 56.

A damper in air duct controls the amount of air supplied to the room.This damper is operated in response to a thermostat 54 in the room III.-In winter the thermostat 54 will be set to close the damper 55 when theroom gets too warm and to open it when the room gets cold. In summer thethermostat will operate to open the damper when the room gets too warmand close it when the room gets coolenough.

In order to limit operation of the heating system to certain. periods ofthe day only, and to prevent operation at the peak periods of the powercompanys operation demand, a clock 58 is provided. Assume that the peakperiod of current demand is between 4:30 and 8:30 p. m., and that thetemperature desired in the room is degrees F. The thermostat 54 will beset for 75 degrees. Then at some time prior to 4:30, say at 2:30 thethat the thermostat is set for degrees. A few minutes before 4:30thetime clock 58 will operate relay switches 5| thru wires 52 and 53 andrelay switch 13 thru Wires 51 and to stop pump 4| clock will operatemotor thru wires 69 and 10 to close damper 12 in the fresh air inlet l3.

The system may be converted into a cooling system by rotating shaft 15thru degrees by means of crank 14. Valves 20 and 36 are operated bycrank 14 as are also valves 21 and 16 as will appear. On the end ofshaft 15 is an arm 18 the ends of which are connected by links 19 and 80with arms 8|- and 32 to valves 21 and 16. At 71 is an expansion valvethru which retiming time clock 56 will actuate thermostat 54 thru wires65 and 66 in such a way At the-same time the timeare so that passage 23will connect pipesv l9 and 22 and passage 24 will connect pipes l8 and2|;

passage 38 in valve 36 will connect pipes 43 and 34 and passage 31 willconnect pipes 33 and 45. Refrigerant from the compressor will now passthru pipe 22 into coils 32. Water from pipes 34 and 33 will condense therefrigerant in the shell 3|. This refrigerant is then expanded thruvalve 11 into coils 26 where it takes up heat from the air passing overthe coils to cool the air and warm the refrigerant.

When operating as a cooling system the clock is not operated since thereusually are no peak load periods in the summer and consequently it isnot necessary to limit capacity operation to certain portions of theday.

Whereas we have disclosed in the drawings, Figures 1 and 2, only thesimple conditioning steps of preheating and reheating, there are manyother simple steps in the heating cooling cycle which can be applied tothis system.

In summer it is desirable in many installations using the spit system todeliver dry air at a moderate temperature. To accomplish this it isexpedient-to install a reheating coil 90 subsequent to the precoolingand dehumidifying coils. If the conditioned air is desired at a moderatetemperature, say 70 to '75 degrees, the water after leaving theprecooling coils 40 is warm enough for this purpose. The artesian orwell water is then piped first through the-precooling coils,countercurrently, then through the reheating coil 90, counter-currently,and then to the refrigeration condenser. An. added advantage of thismethod is the reduced water temperature in the condensers, this reducingthe power input to the compressors and increasing the refrigeratingtonnage on the dehumidifying or refrigerant coils,-reducing the dewpoint produced by the system. I

If air at a warmer temperature is desired than '10 to degrees in summeran eflicient method is to add on a secondary reheating coil 9| throughwhich the hot refrigerant liquid is circulated counter-currently beforepassing through the expansion valve 11 and on to the dehumidifying orrefrigerant cooling coils 26. The use of colder liquid through theexpansion valve further reduces the dew point produced by the system.

A further advantage of this system is the use of the same boil 9! as asuperheat removal coil in winter, thus reducing the total amount of coilsurface'required for refrigerant condensing and air reheating in winter.By-passing the expansion valve is necessary.

Another simple but not so economical arrangement is to feed the summerreheating water coil described above with water from the refrigerantcondensers. This water will be about 90 degrees, and will' give degreeair delivery if necessary.

Another obvious addition to this system is a humidifying spray over thepreheating 'coils in winter. Such a spray enhances the heat transferfrom the coils and also provides cheap low temperature energy. Thehumidified air delivcred can have a lower temperature and create aneffect of warmth due to the increased moisture content. at a reducedoperating cost, since them.

well water-is ordinarily much cheaper than reverse cycle refrigeratingenergy.

The use of freon refrigeration in this cycle demands the arrangement ofsuperheating and liquid reheating coils above the condensers so that thecoil may be purged back to the com-.

pressors or trap. The winter water cooling refrigerant heating coilsshould be arranged to drain directly back to the compressors. Theinvention is deemed, therefore, to include these and other combinationsnot inconsistent with It is also to be understood that the abovemodifications will be capable of many simple and intricate controlschemes which may be used. For example, some of the well water may besprayed over the warm side of the preheating coils in winter undercontrol of the air'temperature leaving'these coils. For more extremehumidification when little out door air is needed for infiltrationrepression, well water may be sprayed over the superheat coils in a finefilm under the control of the leaving air temperature or the humidity ofthe treated spaces. In summer it is obvious for an extreme degree ofreheating without loss of energy that the amount of water going thru theprecooling coils should be throttled as required to give the maximum airtemperature leaving the unit. I

It will be obvious to those skilled in the art that various changes maybe made in the invention without departing from the spirit thereof, we,therefore, do not limit ourselves to the invention as shown in thedrawings and described in the specification but only as set forth in theappended claims.

What we claim is:

1. A heating system comprising a compressor, a condenser and anevaporator, means for causing the air from the chamber to be heated topass over the condenser to condense the gas therein and to warm the air,a water circulating pump connected to a source of water having a normaltemperature within a few degrees of the temperature desired in the room,and means for transferring some of the heat from this water to the airprior to contact of the air with the said condenser.

' 2. In a system for heating a building with the reversed refrigeratingcycle comprising a refrigerant compressor, condenser receiver andevaporator, means for withdrawing air from the chamber to be heated andcirculating it in heat exchange relation with the said condenser tocondense the refrigerant therein and warm the air, a water circulatingpump having a natural source of supply at a temperature within arelatively few degrees of the temperature desired .in the building,means for supplying outside air to the said building, means forpre-warming this outside air by the water from said pump and means forthereafter using said water as a heating means for the evaporatedrefrigerant in 4. A heating system of the kind described comprising incombination a refrigerating cycle,

means for circulating air fromxand into a chamber to be heated, meansfor heating the air so circulated by heat developed by the compressor ofthe refrigerator system, means for supplying artesian water to warmevaporated refrigerant. in said refrigerating system, meansfor supplyingoutside air to the chamber to be heated and means for pre-warming thisair by I the saidartesian water prior to its passage to the refrigerantevaporator.

5. A system of the kind described comprising the combination with a roomto be heated of means for circulating air from and back into the room,means for heating said air, means for supplying additional air to saidroom, means for circulating artesian water in heat exchange relationwith said entering air to pre-warm said air, and timing means formaintaining operation of said heating means and said water circulatingmeans only at predetermined times in the day.

6. A heating system for a room comprising a compressor, a condenser andan evaporator, means for causing the air from the room 'to be heated topass over the condenser to condense the refrigerating gas deliveredthereto by causing it to pass over said condenser prior to its entryinto the room and a pump for circulating water in heat exchangerelationwith the atmospheric air entering the room whereby some of theheat from the water is imparted to the incoming air prior to contact ofsaid air with the said condenser.

'7. A convertible air conditioning system'comprising means forcirculating water from a natural source thereof, a refrigerating-systemincluding a compressor, a first heat exchange de-.

vice in contact with the air to be conditioned, and a second heatexchange deviceincontactwith the water circulated by said circulatingmeans; means whereby the water-is brought into heat exchange relationwith the air to beconditioned prior to contact of the air with saidfirst heat -the compressor-and to warm the air, means for supplyingatmospheric air to said room and for exchange device; and'a system ofcontrol valves for controlling the'flow of refrigerant in saidrefrigerating system whereby, in one position of the valves, therefrigerant may be caused to flow in succession through said first heatexchange device and thereafter through said second heat exchange deviceand, in, another position of the valves, the refrigerant may be causedto flow in-succession through said second heat exchange device andthereafter through said first heat exchange device.

KEMPER P. BRACE.

ROBERT B. P; CRAWFORD.

